An endoscope system includes, for example, a scope (endoscope) to be inserted into body cavities, a light source device and a video processor that are connected to that scope, a monitor device, and the like.
In body cavities, it is completely dark because there is no external light, and accordingly a light source device is necessary. A scope has, at its tip portion or the like, an image pickup device such as a CCD or the like and an outlet port for light (white light/RGB light or the like, which will be referred to as diagnosis light hereinbelow) provided by the light source device.
It has been necessary for alight source device to adjust an amount of light, for example because a necessary amount of light varies between direct observation and a picking up of images, because an appropriate amount of light varies in accordance with target sites, or because a necessary amount of light varies in accordance with distance between an observation target and the tip of the endoscope. For example, when the distance is small, a light amount is reduced so as to prevent blown-out highlighting from occurring in endoscopic images, and when the distance is great, a light amount is increased so that dark sites can be observed. This adjustment of a light amount is performed, for example, by switching between different lamps, varying electric power to be supplied to lamps, adjusting a diaphragm, or by using other means. This adjustment of a diaphragm is implemented according to the operation angle of diaphragm blades.
A conventional art and a background related to the above endoscope system are disclosed by, for example, Japanese Laid-open Patent Publication No. S60-232523.
Also, as disclosed by, for example, Japanese Laid-open Patent Publication No. H03-21219, the light source device of the above endoscope has conventionally used light of the colors of R (Red), G, (Green), and B (Blue), and etc. as illumination light (diagnosis light).
Also, as disclosed by Japanese Laid-open Patent Publication No. H03-21219 above, a frame sequential method and a color mosaic method (also referred to as a simultaneous method) are known as color image pickup methods for an electronic scope. As a frame sequential method, a method in which illumination light is switched to R (Red), G, (Green), and B (Blue) sequentially is known, as disclosed by, for example, Reference Document 1 (Japanese Laid-open Patent Publication No. S61-82731). As a color mosaic method, a method in which a filter array arranges, in a mosaic manner and on the front plane of the solid image pickup element, color transmission filters transmitting the colors R, G, B, and etc. is known, as disclosed by, for example, Reference Document 2 (Japanese Laid-open Patent Publication No. S60-76888). For a color mosaic method, the above diagnosis light is white light.
Also, as an example of a light source device of the above endoscope system, there is a configuration that includes a processor to control the entire light source device (referred to as a main CPU) and a processor dedicated to the function of adjusting a light amount (light adjustment function) (referred to as a computation dedicated CPU).